Switch break jaw and spring means

ABSTRACT

An electrical switch break jaw of the type formed in the shape of a U with an arcuate spring member supported by apertures in the walls of the jaw, wherein the arcuate spring provides a means for insuring a firm grip jaw and a means whereby the gap in the jaw remains constant.

United States Patent [72] Inventor Chi-Tan Hung No. l4-l Yen Ping SL, Ku Shan. Kao l-lsiung. Chlnn 'Tliwan [2|] Appl. No. 823.562 [22] Filed May [2, I969 [45] Patented Aug. 10, I971 [54] SWITCH BREAK .IAW AND SPRING MEANS 5 Claims, 4 Drawing Figs.

[52] U.S.Cl 200/166!) [SI] Int. CL 4 r i i "01h 1/42 [50I l 'ieldolsearch 200/166E, I70; 339/253, 258 F, 259 F [56] Reterences Cited UNITED STATES PATENTS 1,589,066 6/1926 Gibbons 200/166 E l,983,28l 12/1934 Fries ct al. i 200/166 E Primary Examiner-H. 0. Jones Attorney-Lane, Aitken, Dunner & Ziems ABSTRACT: An electrical switch break jaw of the type formed in the shape of a U with an arcuate spring member supported by apertures in the walls of the jaw, wherein the arcuate spring provides a means for insuring a firm grip jaw and a means whereby the gap in the jaw remains constant.

PATENTED AUG] 0:97:

INVENTOH CHI-TSAN HUNG SWITCH BREAK .IAW AND SPRING MEANS BACKGROUND OF THE INVENTION Conventional switch break jaws are ordinarily made from a metal strap which is formed in the general shape of a U. The upper part of the U is folded inward to form inwardly folded legs. The material forming the jaw must have suitable electric conductivity and elastic properties. Alloys of copper, bronze, and phosphor bronze have been found to satisfy this require ment. During normal use, the gap separating the two fold-in legs becomes widened. Continued use causes metal fatigue resulting in the loss of the elastic properties of the metal so that when the inwardly folded legs are displaced from each other, they will not return to the predetermined gap distance. The gap, which was designed to receive a plug or switch blade becomes so wide that there is no longer a friction fit between the inwardly folded legs of the jaw and the plug or switch blade. When the friction fit is lost electrical contact can no longer be accomplished and the jaw must be repaired or replaced. The general remedy to restore the friction fit and hence electrical contact and firm grip is to mechanically adjust the legs. This procedure is both costly and unreliable. In accordance with the present invention, an arcuate spring member resiliently pressing the legs provides means for maintaining a constant gap in the break jaw and excellent electrical contact.

SUMMARY OF THE INVENTION The present invention relates to a new type of switch break jaw. The improved jaw contains an arcuate spring member which resiliently presses the legs of the jaw and provides a means for urging the legs against the plug or switch blades which are inserted into the jaw.

Among the objects of the present invention is to provide a switch break jaw with a means therein to prevent widening of the jaw during normal operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of the prior art switch break aw;

FIG. 2 is a front view of the switch break jaw of the present invention;

FIG. 3 is a side view of the jaw shown in FIG. 2; and

FIG. 4 is a perspective view of a plurality of switch break jaws of the present invention in an electrical receptacle.

DESCRIPTION OF THE PREFERRED EMBODIMENT A conventional switch break jaw formed of a metal strap is shown in FIG. I. The strap is usually made from alloys of copper and bronze which have suitable electrical conductivity and elastic properties. Switch break jaw 10 is formed in the general shape ofa U and has legs I I which are folded inwardly and separated from each other to form gap I2. During normal operation, electrical contact is made between legs II and plug blades (not shown). Through repeated insertion and removal of blades, gap 12 increases and with prolonged use gap 12 may become so large that electrical contact can no longer be made. The elastic properties of the metal-forming jaw l0 cannot be depended upon to maintain gap 12 at a distance which will grip blades indefinitely.

In FIG. 2 the switch break jaw of the present invention is shown which, like the prior art, is in the general shape of the U with a flat floor 15 having a fastening aperture 17 for securing the unit in an electrical receptable. The jaw 10 is provided with sidewalls 14 which if extended would meet and form an isosceles triangle but sidewalls I4 are bent inwardly toward each other at 16 to form inwardly folded legs ll. The inwardly folded legs 11 are separated from each other to form gap 12. Cut out of each sidewall 14 is aperture 18. Aperture l8 receives and supports an arcuate spring member 20 which is formed of a resilient material such as steel wire in the sh a e of a C wlth a diameter large enough so as not to interfere wit the insertion of blades into the jaw. Spring member 20 is planted with open ends 22 against the outer surfaces of infolded legs 11 in order that the resilient force of the spring member continuously presses the legs of the jaw inward. When a contact blade is inserted between the legs 11, the spring member 20 urges the legs 11 into good electrical contact with the blade. The amount of force produced by the spring member can be controlled by elastic properties of the metal used and by the diameter of the member. Thus a switch break jaw capable of electrical contact after prolonged use is provided. A plurality of switch break jaws may be mounted on an electrical receptacle as shown in FIG. 4.

By providing a switch break jaw with an arcuate spring member in accordance with the present invention, loss of electrical contact during repeated use is greatly reduced and the resilient action of the spring member provides a firm grip between the jaw and plug blades after prolonged use.

lclaim:

I. An electrical switch break jaw of the type formed of a metal strap in the general shape of a U, at least one of the walls of said jaw defining an aperture therein, said strap further forming inwardly folded legs secured to said walls so that the inner opposed faces of said inwardly folded legs define a gap substantially parallel to said walls of said jaw and having a predetermined width and being capable of receiving and securing an electrical element therein, wherein the improvement comprises means having at least a portion thereof supported by at least one of said apertures for resiliently pressing the outer opposed faces of said inwardly folded legs inwardly toward each other to prevent permanent widening of said inwardly folded legs during operation of the switch break jaw, wherein the means for resiliently pressing said inwardly folded legs inwardly is an arcuate spring member defining a pair of open ends, one of said pair being in contact with one of said inwardly folded legs, and having an intermediate portion thereof supported by said aperture so that the other of said pair of open ends presses the other of said inwardly folded legs toward said one of said inwardly folded legs.

2. The jaw according to claim 1 wherein each of the opposing walls of said jaw has an aperture formed therein which together provide support for at least two intermediate portions of said arcuate spring member.

3. The jaw according to claim 2 wherein said arcuate spring member is formed of a resilient material.

4. The jaw according to claim 3 wherein said resilient material is steel wire.

5. The jaw according to claim I wherein said spring member is generally C-shaped, the ends of which respectively engage the outer walls of said inwardly folded legs in a direction which is substantially normal to the outer opposed faces of said inwardly folded legs. 

1. An electrical switch break jaw of the type formed of a metal strap in the general shape of a U, at least one of the walls of said jaw defining an aperture therein, said strap further forming inwardly folded legs secured to said walls so that the inner opposed faces of said inwardly folded legs define a gap substantially parallel to said walls of said jaw and having a predetermined width and being capable of receiving and securing an electrical element therein, wherein the improvement comprises means having at least a portion thereof supported by at least one of said apertures for resiliently pressing the outer opposed faces of said inwardly folded legs inwardly toward each other to prevent permanent widening of said inwardly folded legs during operation of the switch break jaw, wherein the means for resiliently pressing said inwardly folded legs inwardly is an arcuate spring member defining a pair of open ends, one of said pair being in contact with one of said inwardly folded legs, and having an intermediate portion thereof supported by said aperture so that the other of said pair of open ends presses the other of said inwardly folded legs toward said one of said inwardly folded legs.
 2. The jaw according to claim 1 wherein each of the opposing walls of said jaw has an aperture formed therein which together provide support for at least two intermediate portions of said arcuate spring member.
 3. The jaw according to claim 2 wherein said arcuate spring member is formed of a resilient material.
 4. The jaw according to claim 3 wherein said resilient material is steel wire.
 5. The jaw according to claim 1 wherein said spring member is generally C-shaped, the ends of which respectively engage the outer walls of said inwardly folded legs in a direction which is substantially normal to the outer opposed faces of said inwardly folded legs. 